Many medical procedures utilize elongate flexible guidewires for guiding the insertion of catheters, scopes or other instruments into ducts, passageways, vessels or cavities of the body.
In particular, certain diagnostic and/or interventional cardiovascular procedures (e.g., cardiac catheterization, percutaneous transluminal coronary angioplasty, etc. . . . ) utilize guidewires to facilitate the insertion and advancement of catheters to specific locations within the cardiac and/or vascular anatomy. It is the usual practice, in such cardiovascular procedures, to, percutaneously insert the guidewire, through an introducer, into a peripheral blood vessel. The guidewire is then advanced to a point where the distal end of the guidewire is positioned at or near a target lesion or anatomical structure. Thereafter, a selected catheter or instrument is advanced over the pre-positioned guidewire to the desired treatment location.
Also, in some gastroenterologic procedures, guidewires are utilized to guide the advancements of catheters, endoscopes or other instruments through various portions of the gastrointestinal tract or biliary tree. For example, one gastroenterologic procedure, known as Endoscopic Retrograde Cholangiopancreatography (ERCP), a duodenoscope is inserted transesophogeally and advanced into the duodenum. The duodenoscope is then utilized to visually locate an opening, known as the ampulla of Vater, through which the Common Bile Duct enters the gastrointestinal tract. A guidewire is then passed through a working channel of the duodenoscope, and into the ampulla. The guidewire is then advanced through the Common Bile Duct into the Pancreatic Duct. With the guidewire positioned in the Pancreatic Duct, a small catheter is then advanced over the guidewire and into the Pancreatic Duct, whereat such catheter may be used to inject radiopaque dye and/or for collecting pancreatic secretions for cytological analysis.
Other types of medical procedures which utilize guidewires include various urological and gynecological procedures wherein it is desirable to pass a flexible scope, catheter or other instrument over a prepositioned guidewire to a target location within a duct, organ or anatomical passageway of the body.
At least some of the guidewires utilized in medical procedures are formed of a longitudinal wire core having a continuous coil of thin steel wire tightly wound thereabout. Such guidewires typically have an outer diameter of less than 0.1 inches and, in many instances, approximately 0.008-0.040 inches. The coiled outer surface of the guidewire may be covered with a smooth, physiologically inert coating such as a fluorocarbon (e.g., Teflon.TM. E. I. Dupont de Neumours Corp., Wilmington, Del.) or silicone (e.g., MTX Coating, Dow Corning, Midland, Mich.).
Advancement of a guidewire to a desired location within a passageway or vessel may be difficult or impossible in cases where there exists a total or near-total blockage of the passageway or vessel. For example, in percutaneous transluminal coronary angioplasty (PTCA) procedures, the presence of a complete occlusion within the lumen of a diseased coronary artery may prevent the tip of a guidewire from being advanced through such occlusive lesion such that an angioplasty catheter may subsequently be advanced to a proper operative location adjacent the occlusive lesion. In such instances, the inability to advance the guidewire through the fully occluded coronary vessel may necessitate abandonment of the PTCA procedure and/or the election of an alternative, more invasive, procedure such as cardio-thoracic surgery. Thus, it would be highly desirable to develop a guidewire which is capable of safely boring or creating a tunnel or passageway through a total or near-total occlusion.
Another problem which may be encountered during guidewire assisted cardiovascular procedures (e.g., PTCA) is the occurrence of vasospasm or involuntary contraction of the blood vessel into which the guidewire has been inserted. The occurrence of such spasm or contraction may necessitate the administration of vasospasm relaxing pharmacologic agents. The occurrence of such blood vessel spasm may severely compromise the hemodynamic function of the blood vessel, with potentially serious secondary effects (e.g., infarction of tissue due to disruption of blood supply). Thus, it would be highly desirable to develop a guidewire capable of delivering a non-pharmacologic vasorelaxant treatment directly to the blood vessel. One type of non-pharmacologic, vasorelaxant treatment which may be utilized for this purpose is the delivery of ultrasonic vibration to the blood vessel wall. See, Chokahi, S. K., et al., Ultrasonic Energy Produces Endotheliel Dependent Vasomotor Relaxation In Vitro, (Abstract) 62nd Scientific Sessions, American Heart Association (1989); Fischell, T. A., et al., Ultrasonic Energy: Effects on vascular Function and Integrity; Circulation; 84:1783-1795 (1991)
One prior ultrasound-transmitting wire is disclosed in U.S. Pat. No. 5,156,143 (Bocquet, et al.) entitled ULTRASONIC PERCUSSION DEVICE.
The device disclosed in U.S. Pat. No. 5,156,143 comprises an elongate wire member of constant diameter which is purportedly insertable into a blood vessel to transmit ultrasonic energy from an extracorporeally located ultrasound generating device, to a location within the blood vessel. The ultrasonic vibrations at the distal end of the device are purportedly capable of destroying obstructive material (i.e. atheromata) within a blood vessel by way of ultrasonic percussion.
There exists a need in the art for the invention and development of improved ultrasonic guidewires capable of transmitting ultrasonic energy from an ultrasound generation device located outside the body to a site within the body for purposes of a) ablating, boring or through an existing mass of obstructive matter and/or b) reversing or preventing untoward spastic or constrictive activity in at least some anatomical ducts, passageways and vessels of the body.